BLADDER TRANSPLANTATION: THE NEW FRONTIER IN ABDOMINAL ORGAN TRANSPLANTATION

ABSTRACT Lower urinary tract abnormalities are directly implicated in the etiology of renal dysfunction in 6 to 24% of dialytic patients. These patients require bladder capacity and compliance readjustment before being considered viable candidates for renal transplantation. Vesical augmentation surgeries often involve the use of intestinal segments. Although these procedures can effectively restore bladder capacity and compliance, they present various issues related to maintaining mucous absorption and secretion capacity. Acidosis, recurrent urinary tract infections, and stone formation are extremely common, leading to frequent hospitalizations and graft function loss. Urinary tissue is certainly ideal for these reconstructions; however, bladder augmentation using ureter and renal pelvis are feasible only in a minority of cases. Experimental studies have been conducted to establish the groundwork for vascularized bladder transplantation. Last year, for the first time, this procedure was performed on a brain-dead patient. During this intervention, cystectomy was performed with preservation the vascular pedicle, followed by organ reimplantation. The graft remained viable for a period of 12 hours post-transplant. However, this intervention utilized a robotic platform, making it less reproducible in a multi-organ procurement setting as well as for most transplant centers. Moreover, it is debatable whether the benefits of exclusive bladder transplantation outweigh the risks associated with immunosuppression. For patients needing renal transplantation and requiring lower urinary tract reconstruction, however, utilizing the donor’s bladder may offer an attractive alternative, avoiding the inherent complications of enterocystoplasty without increasing immunological risk. Combined kidney and bladder transplantation has the potential to emerge as the next frontier in abdominal organ transplants.

Trabalho realizado no 1 Serviço de Cirurgia Geral e Aparelho Digestivo, Departamento de Clínica Cirúrgica, Faculdade de Medicina, Universidade Federal de Goiás, Goiânia, GO, Brasil; 2 Serviço de Endoscopia, Hospital das Clínicas e Departamento de Gastroenterologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil; 3 19 .Despite this pioneering human intervention, the robotic harvesting route presents challenges, rendering it impracticable for most transplant services due to extended surgical times and the logistical demand for immediate robotic technology access, compounded by the complexity of multidisciplinary organ retrieval efforts.Furthermore, robotic organ reimplantation is beyond the technical capabilities of many surgeons, constraining the number of teams capable of conducting such transplants.
Considering the relative satisfaction with enterocystoplasty outcomes despite their complications, the net benefit of bladder transplantation may not justify the associated immunosuppression risks.Nevertheless, in cases requiring both procedures, kidney transplantation and bladder enlargement, the utilization of bladder tissue from the digestive system could be circumvented without additional immunosuppression risks.Utilizing kidneys and bladders from the same deceased donor and performing both transplants simultaneously should not alter antigen exposure; thus, no additional immunological impact on renal transplant success is anticipated.Additionally, this approach spares the patient from undergoing two separate surgical procedures and reduces dialysis duration by eliminating the wait for bladder enlargement and recovery before kidney transplant eligibility.
From an immunological perspective, the bladder, predominantly composed of muscle tissue and devoid of lymphoid structures, is hypothesized to exhibit a rejection profile akin to cardiac grafts, which require lower immunosuppression doses compared to kidney grafts.Consequently, in combined kidney and bladder transplants, immunosuppression regimens may not necessitate modification.

CONCLUSIONS
In summary, dual kidney and bladder transplantation presents a logical intervention for patients on renal replacement therapy with neurogenic bladder who require bladder augmentation prior to kidney transplantation.The successful transplantation of a uterus from a deceased donor, another muscular pelvic organ, corroborates the feasibility of this approach 4,6,10 .Bladder transplantation, in conjunction with kidney transplantation, may represent the next frontier in abdominal organ transplantation.

INTRODUCTION
A multitude of conditions can compromise bladder integrity, leading to a loss of the organ's capability to store urine at low pressures.These conditions frequently contribute to renal function deterioration and the subsequent need for renal replacement therapy.In the United States, urinary tract anomalies are implicated as a causative factor in renal function loss in approximately 6% of kidney transplant recipients 9 .This incidence escalates to 24.1% in pediatric patients due to congenital anomalies affecting the lower urinary tract, such as myelomeningocele, posterior urethral valves, and spina bifida 24 .Similarly, in Brazil, 35% of transplanted children have urological anomalies as the primary etiology of renal function loss 17 .While kidney transplantation is acknowledged for its cost-effectiveness and enhancement of patient survival and quality of life compared to dialysis, a prerequisite for successful renal transplantation in these patients is the optimization of the lower urinary tract to prevent compromise to the graft, as observed in native kidneys 11,21 .
The inaugural urinary diversion utilizing an intestinal segment was executed by Von Mikulicz in 1889 25 , with routine application following Couvelaire's publication in 1950 7 .It was not until two decades later that the first kidney transplants in patients with urinary reconstructions involving intestinal segments were reported 16,22 .Presently, bladder capacity augmentation through an ileal segment is the most commonly employed method for such reconstructions.Despite its effectiveness in increasing capacity and compliance, the intestinal segment continues to absorb urinary toxins, potentially leading to acidosis and premature dialysis requirement due to its absorptive function 5 .Additionally, the maintenance of mucus secretion contributes to the formation of urinary stones, with an incidence ranging from 14 to 52% 27 .
Furthermore, these patients frequently experience bacteriuria and urinary tract infections, with incidences reported between 50 to 70% 9 .Among the 116 patients who underwent kidney transplantation after enterocystoplasty at our institution, 79% experienced recurrent pyelonephritis.
Long-term exposure of urine to intestinal mucosa may induce malignant transformations, culminating in adenocarcinoma development.Enlarged bladders with an ileal segment present a tumor incidence of about 5%, often manifesting years postprocedure 3 .While the urinary tract tissue remains the ideal medium for bladder augmentation, the use of remodeled ureter, pelvis, and calyces as a bladder flap is infrequent, due to typically insufficient capacity 18 .Several alternative methods for bladder expansion have been explored, but none have yet become standard practice due to less than satisfactory results 1,2 .
The concept of using a non-pedicled bladder flap sutured to the recipient's bladder was first reported by Calzada from the University of Malaga in 1987 14 .Subsequent isolated case reports have utilized non-pedicled bladder grafts to facilitate ureteral reimplantation, rather than to increase storage capacity 8,12,15,20 .More recent experimental studies have investigated pedicled bladder grafts, such as the combined kidney and bladder transplant in swine conducted by Torino from the University of Rome in 2013 23 .However, these have encountered varying success rates, with some animals requiring exploratory laparotomy within days due to graft thrombosis, presumably from rejection 26 .
To lay the groundwork for human bladder transplantation, cadaveric models were also developed to elucidate organ perfusion and possible anatomical variations, with a focus on arterial irrigation 13 .In 2023, Nassiri and Gill conducted the first human pedicled bladder transplantation in a non-organ-donation candidate brain-dead patient after extensive pre-clinical studies in pigs and pulsatile cadavers.The procedure included robotic Serviço de Cirurgia do Fígado, Hospital das Clínicas e Departamento de Gastroenterologia, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil Como citar esse artigo: de Biase Silva-Neto WB, Quirese C, De Moura EGH, Coelho FF, Herman P. A queda da pressão portal após desvascularização esofagogástrica e esplenectomia /10.1590/0102-672020210001e1581A QUEDA DA PRESSÃO PORTAL APÓS DESVASCULARIZAÇÃO E ESPLENECTOMIA INFLUENCIA A VARIAÇÃO CALIBRE DAS VARIZES E AS RESSANGRAMENTO NA ESQUISTOSSOMOSE NO SEGUIMENTO EM LONGO PRAZO?Does the drop in portal pressure after esophagogastric devascularization and splenectomy variation of variceal calibers and the rebleeding rates in schistosomiasis in late follow-up?Walter de Biase SILVA-NETO 1 , Claudemiro QUIRESE 1 , Eduardo Guimarães Horneaux de MOURA 2 , Fabricio Ferreira COELHO 3 , Paulo HERMAN 3 ABSTRACT -Background: The treatment of choice for patients with schistosomiasis with previous episode of varices is bleeding esophagogastric devascularization and splenectomy (EGDS) in association with postoperative endoscopic therapy.However, studies have shown varices recurrence especially after long-term follow-up.Aim: To assess the impact on behavior of esophageal varices and bleeding recurrence after post-operative endoscopic treatment of patients submitted to EGDS.Methods: Thirty-six patients submitted to EGDS portal pressure drop, more or 30%, and compared with the behavior of esophageal varices and the rate of bleeding recurrence.Results late post-operative varices caliber when compared the pre-operative data was observed despite an increase in diameter during follow-up that was controlled by endoscopic therapy.Conclusion variceal calibers when comparing pre-operative and early or late diameters.The comparison between the portal pressure drop and the rebleeding rates was also not HEADINGS: Schistosomiasis mansoni.Portal hypertension.Surgery.Portal pressure.Esophageal and gastric varices.